.page-about {
  --about-gap: clamp(52px, 9vw, 108px);
  --about-cut: 16px;
  padding-bottom: clamp(56px, 9vw, 120px);
  overflow-x: clip;
}

/* ---------- 页首 ---------- */
.page-about .breadcrumbs {
  margin: 22px 0 0;
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--silver);
}

.page-about .about-head {
  position: relative;
  padding-block: clamp(22px, 4vw, 42px) clamp(24px, 4vw, 40px);
  border-bottom: 1px solid var(--wire);
}

.page-about .about-head::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -1px;
  width: clamp(64px, 14vw, 158px);
  height: 2px;
  background: var(--cyan);
}

.page-about .about-head .page-head__title {
  font-family: var(--font-display);
  font-size: clamp(27px, 6.2vw, 50px);
  line-height: 1.14;
  letter-spacing: 0.01em;
  color: var(--white);
  margin: 12px 0 18px;
  max-width: 20ch;
}

.page-about .about-head .page-head__lede {
  color: var(--silver);
  font-size: clamp(15px, 1.7vw, 16.5px);
  line-height: 1.85;
  max-width: 64ch;
  margin: 0 0 28px;
}

.page-about .about-head__facts {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(122px, 1fr));
  gap: 14px 20px;
  list-style: none;
  margin: 0;
  padding: 0;
}

.page-about .about-head__fact {
  border-left: 1px solid var(--wire);
  padding-left: 12px;
}

.page-about .about-head__fact b {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(22px, 4.4vw, 30px);
  line-height: 1;
  font-weight: 600;
  color: var(--cyan);
  letter-spacing: -0.01em;
}

.page-about .about-head__fact span {
  display: block;
  margin-top: 6px;
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--silver);
}

/* ---------- 章节头 ---------- */
.page-about .section {
  padding-block: var(--about-gap) 0;
}

.page-about .section__head {
  display: flex;
  align-items: flex-start;
  gap: 14px;
  margin-bottom: clamp(24px, 4vw, 44px);
}

.page-about .section-num {
  font-family: var(--font-mono);
  font-size: clamp(22px, 4vw, 30px);
  line-height: 1.05;
  color: var(--cyan);
  opacity: 0.45;
  flex: 0 0 auto;
  padding-top: 2px;
  transition: opacity var(--t-base);
}

.page-about .section.is-active .section-num {
  opacity: 1;
}

.page-about .section__title {
  font-family: var(--font-display);
  font-size: clamp(21px, 3.5vw, 31px);
  line-height: 1.26;
  color: var(--white);
  margin: 0;
}

.page-about .annotation {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.24em;
  color: var(--cyan-deep);
  margin: 8px 0 0;
}

/* ---------- 起点 ---------- */
.page-about .origin-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(24px, 4vw, 44px);
}

.page-about .origin-copy p {
  color: var(--silver);
  font-size: 15.5px;
  line-height: 1.82;
  margin: 0 0 16px;
}

.page-about .origin-copy__link {
  display: inline-block;
  margin-top: 6px;
  font-size: 14px;
  letter-spacing: 0.05em;
  color: var(--cyan);
  text-decoration: none;
  border-bottom: 1px solid var(--cyan-deep);
  padding-bottom: 3px;
  transition: color var(--t-fast), border-color var(--t-fast);
}

.page-about .origin-copy__link:hover,
.page-about .origin-copy__link:focus-visible {
  color: var(--gold);
  border-color: var(--gold);
}

.page-about .origin-media img,
.page-about .chronicle__banner img,
.page-about .cross-media img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  object-fit: cover;
  filter: saturate(0.86) contrast(1.06);
}

.page-about .media-frame__caption {
  position: static;
  margin-top: 10px;
  font-size: 12px;
  line-height: 1.6;
  color: var(--silver);
  opacity: 0.82;
}

/* ---------- 记录准则 ---------- */
.page-about .principles {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: clamp(22px, 3.4vw, 34px);
}

.page-about .principle {
  position: relative;
  border-left: 1px solid var(--wire);
  padding: 2px 0 2px clamp(16px, 3vw, 28px);
}

.page-about .principle::before {
  content: "";
  position: absolute;
  left: -1px;
  top: 5px;
  width: 1px;
  height: 36px;
  background: var(--cyan);
}

.page-about .principle__code {
  display: block;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.2em;
  color: var(--cyan);
  margin-bottom: 10px;
}

.page-about .principle h3 {
  font-family: var(--font-display);
  font-size: clamp(17px, 2.5vw, 21px);
  line-height: 1.4;
  color: var(--white);
  margin: 0 0 10px;
}

.page-about .principle p {
  margin: 0;
  color: var(--silver);
  font-size: 15.5px;
  line-height: 1.82;
}

/* ---------- 维护团队 ---------- */
.page-about .crew {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 16px;
}

.page-about .crew__col {
  position: relative;
  background: var(--panel);
  border: 1px solid var(--wire);
  padding: clamp(18px, 2.8vw, 26px);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - var(--about-cut)), calc(100% - var(--about-cut)) 100%, 0 100%);
}

.page-about .crew__col::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  width: 44px;
  height: 2px;
  background: var(--cyan);
}

.page-about .crew__col:nth-child(2)::before {
  background: var(--archive);
}

.page-about .crew__col:nth-child(3)::before {
  background: var(--gold);
}

.page-about .crew__count {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(26px, 4.6vw, 34px);
  line-height: 1;
  color: var(--white);
  margin-bottom: 8px;
}

.page-about .crew__count--word {
  font-size: clamp(20px, 3.4vw, 24px);
  color: var(--gold);
  letter-spacing: 0.08em;
}

.page-about .crew__role {
  font-size: 13px;
  letter-spacing: 0.08em;
  color: var(--cyan);
  margin: 0 0 14px;
  font-weight: 500;
}

.page-about .crew__col p {
  margin: 0;
  color: var(--silver);
  font-size: 14.5px;
  line-height: 1.8;
}

/* ---------- 编年史 ---------- */
.page-about .chronicle__banner {
  margin: 0 0 clamp(28px, 5vw, 52px);
}

.page-about .chronicle__list {
  list-style: none;
  margin: 0;
  padding: 0;
}

.page-about .chronicle__item {
  position: relative;
  padding-left: 34px;
  padding-bottom: clamp(34px, 5.4vw, 60px);
}

.page-about .chronicle__item:last-child {
  padding-bottom: 0;
}

.page-about .chronicle__item::before {
  content: "";
  position: absolute;
  left: 7px;
  top: 18px;
  bottom: 0;
  width: 1px;
  background: var(--wire);
}

.page-about .chronicle__item:last-child::before {
  background: linear-gradient(180deg, var(--wire), transparent);
}

.page-about .chronicle__item::after {
  content: "";
  position: absolute;
  left: 0;
  top: 9px;
  width: 15px;
  height: 15px;
  box-sizing: border-box;
  border-radius: 50%;
  background: var(--ink);
  border: 2px solid var(--cyan);
  box-shadow: 0 0 0 4px rgba(20, 224, 216, 0.1);
}

.page-about .chronicle__item--now::after {
  background: var(--gold);
  border-color: var(--gold);
  box-shadow: 0 0 0 4px rgba(255, 138, 43, 0.14);
}

.page-about .chronicle__card {
  background: var(--panel);
  border: 1px solid var(--wire);
  border-left: 2px solid var(--cyan-deep);
  padding: clamp(18px, 3vw, 28px);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 14px), calc(100% - 14px) 100%, 0 100%);
}

.page-about .chronicle__item--now .chronicle__card {
  border-left-color: var(--gold);
}

.page-about .chronicle__cardhead {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 12px;
  margin-bottom: 14px;
}

.page-about .chronicle__year {
  font-family: var(--font-mono);
  font-size: clamp(28px, 6vw, 44px);
  line-height: 1;
  color: var(--white);
  letter-spacing: -0.02em;
}

.page-about .chronicle__tag {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.18em;
  color: var(--cyan);
  border: 1px solid var(--cyan-deep);
  padding: 4px 8px;
}

.page-about .chronicle__item--now .chronicle__tag {
  color: var(--gold);
  border-color: var(--gold);
}

.page-about .chronicle__card p {
  margin: 0;
  color: var(--silver);
  font-size: 15px;
  line-height: 1.82;
  max-width: 60ch;
}

/* ---------- 资料互校 ---------- */
.page-about .cross-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(24px, 4vw, 44px);
}

.page-about .cross-copy p {
  color: var(--silver);
  font-size: 15.5px;
  line-height: 1.82;
  margin: 0 0 16px;
}

.page-about .cross-copy p:last-child {
  margin-bottom: 0;
}

/* ---------- 编目方法 ---------- */
.page-about .catalog-lede {
  color: var(--silver);
  font-size: 15.5px;
  line-height: 1.82;
  max-width: 66ch;
  margin: 0 0 clamp(22px, 3.4vw, 34px);
}

.page-about .catalog-list {
  display: grid;
  gap: 10px;
}

.page-about .catalog-item {
  background: var(--panel);
  border: 1px solid var(--wire);
  transition: border-color var(--t-fast);
}

.page-about .catalog-item[open] {
  border-color: var(--cyan-deep);
}

.page-about .catalog-item__sum {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 8px 16px;
  padding: 16px 18px;
  cursor: pointer;
  list-style: none;
}

.page-about .catalog-item__sum::-webkit-details-marker {
  display: none;
}

.page-about .catalog-item__sum:focus-visible {
  outline: 1px solid var(--cyan);
  outline-offset: 2px;
}

.page-about .catalog-item__q {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.14em;
  color: var(--cyan);
  white-space: nowrap;
}

.page-about .catalog-item__t {
  color: var(--white);
  font-size: 15px;
  letter-spacing: 0.02em;
}

.page-about .catalog-item__body {
  padding: 0 18px 18px;
}

.page-about .catalog-item__body p {
  margin: 0;
  color: var(--silver);
  font-size: 14.5px;
  line-height: 1.8;
}

.page-about .catalog-foot {
  margin: clamp(18px, 3vw, 26px) 0 0;
  color: var(--silver);
  font-size: 14px;
  line-height: 1.8;
}

.page-about .catalog-foot a {
  color: var(--cyan);
  text-decoration: none;
  border-bottom: 1px solid var(--cyan-deep);
}

.page-about .catalog-foot a:hover,
.page-about .catalog-foot a:focus-visible {
  color: var(--gold);
  border-color: var(--gold);
}

/* ---------- 走近档案室 ---------- */
.page-about .room-panel {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 14px;
  background: linear-gradient(150deg, rgba(20, 224, 216, 0.06), transparent 58%), var(--panel);
  border: 1px solid var(--wire);
  padding: clamp(20px, 3.4vw, 34px);
  clip-path: polygon(0 14px, 14px 0, 100% 0, 100% 100%, 0 100%);
}

.page-about .room-panel__side {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.2em;
  color: var(--cyan-deep);
}

.page-about .room-panel__body p {
  margin: 0 0 14px;
  color: var(--silver);
  font-size: 15.5px;
  line-height: 1.85;
  max-width: 64ch;
}

.page-about .room-panel__body p:last-child {
  margin-bottom: 0;
}

/* ---------- 下一步 ---------- */
.page-about .about-next {
  margin-top: var(--about-gap);
  padding-top: clamp(26px, 4vw, 44px);
  border-top: 1px solid var(--wire);
  display: grid;
  gap: 18px;
}

.page-about .about-next__lead {
  margin: 0;
  font-family: var(--font-display);
  font-size: clamp(18px, 2.8vw, 23px);
  color: var(--white);
  letter-spacing: 0.01em;
}

.page-about .about-next__links {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

/* ---------- 响应式 ---------- */
@media (min-width: 760px) {
  .page-about .crew {
    grid-template-columns: 5fr 4fr 3fr;
    align-items: start;
  }

  .page-about .room-panel {
    grid-template-columns: 46px minmax(0, 1fr);
    gap: 24px;
    align-items: start;
  }

  .page-about .room-panel__side {
    writing-mode: vertical-rl;
    letter-spacing: 0.34em;
  }
}

@media (min-width: 900px) {
  .page-about .origin-grid {
    grid-template-columns: 5fr 6fr;
    align-items: start;
  }

  .page-about .cross-grid {
    grid-template-columns: 6fr 5fr;
    align-items: center;
  }

  .page-about .chronicle__item {
    padding-left: 52px;
  }

  .page-about .chronicle__item::before {
    left: 7px;
  }

  .page-about .chronicle__card {
    padding: clamp(22px, 2.6vw, 32px);
  }
}

@media (min-width: 1180px) {
  .page-about .principles {
    gap: 36px;
  }

  .page-about .principle {
    padding-left: 32px;
  }

  .page-about .principle p {
    font-size: 16px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .section-num,
  .page-about .origin-copy__link,
  .page-about .catalog-item {
    transition: none;
  }
}